In the installation of drywall (gypsum board) walls, a filling compound, known as drywall compound, is applied to the seams between the adjacent panels to fill those seams. Once the drywall compound is set, it is sanded to produce a smooth, even surface with the adjacent panel surfaces. The dust produced by sanding the drywall compound is an extremely fine powder which tends to stay in suspension in the air for a long period of time. It is a highly pervasive material that can enter the lungs, nose, eyes and even the pores of the skin. It is the single most serious health hazard for drywall workers. In addition, the dust settles on everything near the sanding site and usually requires several cleanings before it has all been collected.
Attempts to solve this problem include those described in Mehrer U.S. Pat. No. 4,062,152 issued Dec. 13, 1977 and Shaw U.S. Pat. No. 4,759,155 issued July 26, 1988.
In Mehrer, a sander has a hollow body with a series of vacuum ports uniformly distributed over a front face of the body, leading into the vacuum chamber. An abrasive, air permeable sheet is clamped over the front face of the body and a vacuum is applied to the inside of the body through a hollow handle connected to the body by a universal joint, in order to draw the sanded off particles into the body and handle.
In Shaw, a similar type of device has a rectangular grid of grooves formed in the front face to distribute the vacuum more uniformly over the back face of the abrasive sheet.
In both of these prior art devices, the body is hollow, with a large internal chamber. This tends to stagnate the flow drawing the dust in through the inlet ports, so that the dust will tend to settle in the body. In addition, even with the grooves of the Shaw patent, the abrasive sheet is supported by ungrooved areas of the sander body front face s that no air flow is possible through the supported portions of the abrasive material.